A multiple-input multiple-output (MIMO) system can provide significant performance gain on the system capacity over the traditional single-input single-output system (SISO); therefore the MIMO system can be a preferred solution to support higher data rate transmission in communications.
However, due to the multi-antenna interference in the receiver, the traditional linear equalizer cannot achieve optimal performance. There are numerous proposals regarding how to improve the signal detecting performance in MIMO communications. These proposals comprise serial interference cancellation, and parallel interference cancellation, among which maximum likelihood sequence detecting (MLSD) is the optimal solution in the sense of minimizing the error probability with impractical high complexity.